Wart Lichen: The Tiny Ecosystem Builder You’ve Probably Already Met
If you’ve ever noticed dark, crusty patches on concrete walls, limestone rocks, or even old tombstones, chances are you’ve encountered wart lichen (Verrucaria deversa) without even knowing it! This unassuming native North American species might not win any beauty contests, but it’s quietly doing important work in our urban and natural landscapes.
What Exactly Is Wart Lichen?
Let’s clear up any confusion right away – wart lichen isn’t actually a plant at all! It’s a fascinating partnership between fungi and algae, working together as one organism. The fungal partner provides structure and protection, while the algae produce food through photosynthesis. It’s like nature’s perfect roommate situation, and it’s been working for millions of years.
Verrucaria deversa gets its wart nickname from the tiny, bump-like fruiting bodies that dot its surface. These dark, crusty patches spread across hard surfaces, creating what looks like a living patina on rocks and concrete.
Where You’ll Find This Hardy Survivor
This resilient lichen is native to North America and has quite the talent for urban living. You’ll typically spot it on:
- Limestone and other calcareous rocks
- Concrete walls and structures
- Old mortar and masonry
- Tombstones and monuments
It’s particularly fond of alkaline surfaces and has an impressive tolerance for air pollution, making it a common sight in cities and towns across the continent.
Is Wart Lichen Good for Your Garden?
While you can’t exactly plant wart lichen like you would a flower, having it appear naturally in your landscape is actually a good sign! Here’s why this little ecosystem builder deserves your respect:
- Air quality indicator: Lichens are sensitive to air pollution, so their presence suggests relatively clean air
- Soil building: Over time, they help break down rock surfaces, contributing to soil formation
- Habitat creation: They provide microhabitat for tiny invertebrates
- Natural patina: They add character and age to stone features and walls
How to Identify Wart Lichen
Spotting Verrucaria deversa is easier than you might think once you know what to look for:
- Appearance: Dark gray to blackish crusty patches
- Texture: Thin, tightly adhering to the surface with small warty bumps
- Location: Almost always on hard, alkaline surfaces like concrete or limestone
- Size: Patches can range from a few inches to several feet across
Living with Wart Lichen
If wart lichen has taken up residence on your garden walls or stone features, consider yourself lucky to be hosting this ancient life form! There’s no need to remove it unless it’s on a surface where you specifically don’t want it. In fact, trying to scrub it off can damage both the lichen and the surface it’s growing on.
If you’re designing a natural or rock garden, leaving existing lichen populations undisturbed will add authenticity and ecological value to your landscape. Just remember – patience is key. Lichens grow incredibly slowly, sometimes less than a millimeter per year, so what you’re seeing may have been decades in the making.
The Bottom Line
Wart lichen might not be the showstopper of your garden, but it’s a fascinating example of nature’s ingenuity and resilience. Next time you spot those dark, crusty patches on a stone wall or concrete surface, take a moment to appreciate this remarkable partnership between fungi and algae that’s been perfecting the art of survival long before the first gardens were ever planted.
